This study was generously supported by Grant R21 DE019213-01 from the National Institute of Dental and Craniofacial Research and the PSRP grant from the Medical College of Georgia (P.I. Franklin R. Tay). We thank Lisha Gu for assistance with the operation of the micro-CT, Jongryul Kim for preparing the completely demineralized specimen in the Supplementary Material, Bob Smith for TEM technical assistance and Michelle Barnes for secretarial support.